In the executive process of a tunneling project, overbreak phenomenon is always one of the most important issues. Nowadays, according to the progress of industry and having new technologies introduced to tunneling industry and their gradual acceptance, traditional methods (drilling and blasting) are replaced by the new methods. Although, the overbreak issue has been largely controlled by project implementers, but it has never been completely eliminated from tunnelling projects. In this research, prediction and optimization of overbreak was discussed using intelligent networks. Best model was selected based on scoring, then it was used for optimization. The R2 and RMSE values of the selected model were 0. 921, 0. 4820, 0. 923 and 0. 4277 for training and testing, respectively. The artificial bee colony (ABC) algorithm, which is one of the new optimization algorithms, was used to optimize these parameters of the blasing pattern. Due to the fact that over break is one of the main problems in tunneling, this reduction can have an important role in the quality and stability of the tunnel. After creating several optimization models and modifying its weights, the optimum amount for the overbreak was 1. 63 m2, which is 47% less than the lowest value achieved during execution process (3. 055 m2 ). The optimal pattern can be obtained with the least possible amount of overbreak.